Progress bar skips from 0% to 100% without updating in between

Question

I am implementing a ProgressBar that updates after a every finished task (with 5 tasks total). It should update by 20% after each finished task. A button click starts running the tasks, but when it is clicked the progress bar goes from 0% to 100% without updating in between. Thread.Sleep(1000) was added before each increment of the progress value to simulate the time each task will take. I want to get the progress bar working before adding the code for each task.

I've tried adding a AvaloniaPropertyChanged event, but it doesn't seem to change the problem.

MainWindow.xaml:

<ProgressBar Name="RunProgress" Value="{Binding Progress}" IsIndeterminate="False" Minimum="0" Maximum="100" Height="30"/>
<TextBlock Text="{Binding ElementName=RunProgress, Path=Value, StringFormat={}{0:0}%}" HorizontalAlignment="Center" VerticalAlignment="Center" />

MainWindow.xaml.cs:

//boolean variables for whether or not that process is completed (false if not done, true if done)
bool MasterLimitsRead = false;
bool MasterOrganized = false;
bool LimitsOrganized = false;
bool RemovedFailed = false;
bool OutputCreated = false;

//holds descriptions of the 5(+1) operations the program runs through including description for Done
string[] operation =
{
   "Reading the master and limits file text",
   "Organizing the master data",
   "Organizing the limits",
   "Identifying and removing failed devices",
   "Creating the output",
   "Done"
};

context.CurrentOp = operation[0];

Thread.Sleep(1000);
MasterLimitsRead = true;
if(MasterLimitsRead == true)
{
   context.Progress += 20;
   context.CurrentOp = operation[1];
}

Thread.Sleep(1000);
MasterOrganized = true;
if(MasterOrganized == true)
{
   context.Progress += 20;
   context.CurrentOp = operation[2];
}

Thread.Sleep(1000);
LimitsOrganized = true;
if(LimitsOrganized == true)
{
   context.Progress += 20;
   context.CurrentOp = operation[3];
}

Thread.Sleep(1000);
RemovedFailed = true;
if(RemovedFailed == true)
{
   context.Progress += 20;
   context.CurrentOp = operation[4];
}

Thread.Sleep(1000);
OutputCreated= true;
if(OutputCreated== true)
{
   context.Progress += 20;
   context.CurrentOp = operation[5];
}

MainWindowViewModel.cs:

private string currentOp = string.Empty;   //variable to store current operation, initialized to empty string
public string CurrentOp
{
   get => currentOp;
   set
   {
      if (value != currentOp)
      {
         currentOp = value;
         OnPropertyChanged();
      }
    }
}

private string progress = 0;   //variable to store ProgressBar value in percent, initialized to 0
public string CurrentOp
{
   get => currentOp;
   set
   {
      if (value != currentOp)
      {
         currentOp = value;
         OnPropertyChanged();
      }
    }
}

public event PropertyChangedEventHandler PropertyChanged;

protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
   if(PropertyChanged != null)
   {
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
   }
}

Expected: Progress bar should increment from 0% to 100% by 20% after each task is complete (simulated by a 1 second delay by the Thread.Sleep(1000))

Actual: Progress bar starts at 0%, then when button is clicked, halts UI interaction for 5 seconds then updates the progress bar to 100%. I want it to update at every increment of value of progress bar.

Answer 1

By calling Sleep you are blocking the UI thread. If UI thread is blocked, there won't be any UI updates. To simulate long-running tasks use await Task.Delay(TimeSpan.FromSeconds(1)) instead.